What Is Depression?

Clinical depression is not just grief or sadness. It is an illness that can challenge the person's ability to perform even routine daily activities. At its worst, depression may lead the person to contemplate or commit suicide. Depression represents a burden for the person and his or her family. Sometimes that burden can seem overwhelming.

Several different types of mood disorders exist.

Major depression is a change in mood that lasts for weeks or months. It is one of the most severe types of depression. Major depression usually involves a low or irritable mood and/or a loss of interest or pleasure in usual activities. It interferes with the person's normal functioning. The person may experience only one episode of depression, but repeated episodes often occur over the person's lifetime.

Dysthymia is less severe than major depression but usually goes on for a longer period, often several years. Usually periods of feeling fairly normal occur between episodes of low mood. The symptoms usually do not completely disrupt the person's normal activities.

Bipolar disorder involves episodes of depression, usually severe, alternating with episodes of extreme elation called mania. This condition is sometimes called by its former name, manic depression. Antidepressant medications may be used for depressive episodes of bipolar disorder, but they are usually combined with other medications indicated for mood stabilization. Caution is warranted because antidepressants may induce mania in individuals with bipolar disorder.

Seasonal depression, which medical professionals call seasonal affective disorder, or SAD, is depression that occurs only at a certain time of the year, usually in winter. It is sometimes called the winter blues. Although SAD is predictable, it can be very severe.

Clinical depression affects about 19 million Americans annually, and it is estimated to contribute to half of all suicides.
Up to 10 percent of people experience at least one major depressive episode during their adult life. Depression affects people of all races, incomes, and ages, but it is more common in elderly people than in young people.

The good news is that depression can be diagnosed and treated effectively in most people. The biggest barrier to overcome is recognizing that someone is depressed and seeking appropriate treatment. Clinical depression always requires attention from a medical or mental health professional.

What causes depression?

The cause of depression is largely unknown, although several theories exist. One theory is that depression is due to the reduced function of one or more neurotransmitter chemicals in the brain such as norepinephrine, dopamine, or serotonin. Another theory that has been researched is that chemical receptor sites may not optimally bind the chemicals serotonin or norepinephrine.

Other factors that may affect why some people are more likely to experience depression include the following:

Risks of depression

Depression interferes with the ability to perform routine daily tasks and take care of oneself or others. Appetite changes, weight loss or gain, energy loss, inability to sleep, or excessive sleep may accompany depression. Suicidal thoughts or actions may eventually occur. People with depression who are not adequately treated may also more frequently have other medical problems.

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